1. Field of the Invention
The present invention relates to a radiation imaging apparatus and a radiation imaging system.
2. Description of the Related Art
In recent years, more and more radiation images like medical X-ray images have been digitized. To capture a radiation digital image, a radiation imaging apparatus that uses, instead of a film, a plurality of radiation detection elements arranged in a two-dimensional matrix to convert a radiation into an electrical signal for image formation has been put to practical use. As an example of this type of radiation imaging apparatus, an X-ray detection apparatus (a flat panel detector (FPD)) has been discussed which includes a two-dimensional matrix of minute X-ray detectors each including a solid-state light detection element stacked on a scintillator that converts X-rays into visible light. The X-ray detection apparatus converts irradiated X-rays into an electrical signal corresponding to the exposure dose.
The digitization of an X-ray image by using an X-ray imaging apparatus including such an X-ray detection apparatus can provide various advantages. For example, the captured image can be immediately examined on a display device for faster diagnosis. Various types of image processing can be easily applied to automate diagnosis and improve the diagnostic accuracy of minute lesions. The absence of a need for a film storage space significantly improves the space efficiency in a hospital.
Little degradation of data during transmission further allows the captured image to be transmitted over a long distance without the degradation. Such a feature may be utilized, for example, to transmit an image captured in a home medical care setting or at a disaster site to a well-equipped urban hospital for a highly-trained doctor's diagnosis.
The system of such an X-ray imaging apparatus typically includes many components aside from an X-ray generation apparatus and an X-ray detection apparatus, including controllers for controlling the respective apparatuses, an image display unit like a display monitor, various interface devices for connecting the two apparatuses, and a large number of cables. For imaging, the X-ray generation apparatus and the X-ray detection apparatus exchange various types of information with each other. Examples include timing information for performing imaging in time with a start and end of X-ray irradiation. Such information is exchanged via various interface devices.
There has been discussed a method using an X-ray detection apparatus that can detect X-ray irradiation and perform imaging without exchanging a signal for adjusting irradiation timing between an X-ray generation apparatus and the X-ray detection apparatus. The use of such an X-ray detection apparatus can simplify the system components because interface devices for connecting the two apparatuses become unnecessary. In addition, a conventional visiting car, for example, that performs film-based imaging may be used to obtain digital images. In X-ray imaging, the management of X-ray doses with which patients are irradiated during imaging is essential. Japanese Patent Application Laid-Open No. 2000-107159 discusses that a control apparatus outside the detector associates image data with X-ray irradiation data.
The transmission of image data may include a gap from the transmission timing of irradiation data, for example, because of communication failure. In such cases, the image data and the irradiation data have sometimes failed to be reliably associated with each other.
Another problem is that the system where the X-ray generation apparatus and the X-ray detection apparatus exchange no irradiation timing includes no unit for communicating various types of information about irradiated X-rays to the X-ray detection apparatus. The various types of information here refer to imaging execution information including an X-ray tube voltage, an X-ray tube current, and irradiation time. The imaging execution information has conventionally been transmitted from the X-ray generation apparatus to a control apparatus and combined with image data transmitted from the X-ray detection apparatus. In contrast, the system where the X-ray generation apparatus and the X-ray detection apparatus exchange no such information has been unable to associate image data with imaging execution information, and sometimes caused a problem in the management of image data.
To address the foregoing problems, imaging execution information including an irradiation condition may be input and associated with image data by using a barcode or from a personal computer (PC). However, such a method entails an additional input operation and may give rise to an erroneous input of information. Setting values input to the X-ray generation apparatus may differ from an actual irradiation condition. Since a PC is needed as an input unit, there has also been the problem of increased system components.